#include<iostream>
struct TreeNode {
     int val;
     struct TreeNode *left;
     struct TreeNode *right;
 };



bool check(struct TreeNode* p,struct TreeNode* q)
{
    if(p==NULL&&q==NULL)return true;
    if(p==NULL||q==NULL)return false;
    if(p->val!=q->val)return false;
    return check(p->left,q->right)&&check(p->right,q->left);
}
bool isSymmetric(struct TreeNode* root){

    return check(root->left,root->right);
}